Tunable Reactive Composite Materials for Bio-Agent Defeat

     This project, funded by the Defense Threat Reduction Agency (DTRA), is focused on developing a combination of reactive fuels materials and biocidal compounds to destroy bio-agents such as anthrax. The fuels, in this case, are reactive nanocomposites that consist of many layers of different metals, with thicknesses ranging from microns to nanometers. When a small amount of energy is supplied to the material, these layers can mix and release large amounts of heat in the process. Further, they can rapidly oxidize and burn at high temperatures.

 

      Below is a high-speed video of Al/Zr reactive particles igniting on a wire and subsequently burning in air. The second video is a similar reaction observed using x-ray phase contrast imaging, allowing for a inside-view of the particles while they are burning.

      This project involves several main thrust areas. The first is to translate fundamental materials knowledge from clean, model powder systems made initially by physical vapor deposition (PVD) and more recently by high energy ball milling, which is a more scalable synthesis method. The second is to understand the various ignition and combustion mechanisms of these reactive powders so that they can be tuned for a wide variety of applications. Particularly, we want to enhance the total heat released by combustion and control the timescale over which that release occurs. This involves understanding how the microstructure, chemistry, and size of the fuel powders impacts their ignition and subsequent burning. Another area is the utilization or development of novel characterization techniques to analyze these materials as they react at extreme temperatures, pressures, or speeds. Examples of these methods are x-ray phase contrast imaging or spectral imaging. The final thrust area is focused implementing these fuels (in conjunction with oxides, etc., as appropriate) in a variety of larger scale bio-agent defeat tests and ultimately determining their performance in real-world applications. These applications, which are primarily focused on bio-agent defeat, involve active collaborations with facilities such as those at the Naval Surface Warfare Center at Indian Head (IHNSWC), the Army Research Labs (ARL), and other academic institutions.

      To use these materials for bio-agent defeat, we mix Al/Mg/Zr-based reactive nanocomposite powders with an iodine precursor/oxide. Upon ignition, the reactive metal powders will supply heat that will burn spores in the vicinity, as well as decompose the solid iodine compound to form hot iodine gas. This gas is released in a dramatic, deep purple cloud that has biocidal properties and can chemically destroy the dangerous spores.

     To use these materials for bio-agent defeat, we will make reactive nanocomposite powders so that they can be mixed with an iodine precursor. Upon ignition, the reactive metal powders will supply heat that will burn spores in the vicinity, as well as decompose the solid iodine compound to form iodine gas. This gas is released in a dramatic, deep purple cloud that has biocidal properties and will chemically destroy the dangerous spores.

     Below is a slow motion video of reactive particles mixing with HIO3, which decomposes into biocidal iodine gas.